The present techniques relates generally to electronic devices. More specifically, the techniques relate to methods and systems for sealing structures in electronic devices.
Certain electronic devices have components that may be sensitive to adverse environmental conditions, primarily to water vapor and oxygen. For example, display devices are commonly used as screens or displays for a wide variety of electronic devices, including televisions, portable and desktop computers, and handheld devices, such as cellular telephones, personal data assistants, and media players. The display components of such devices may display images by producing patterns of light in response to electrical signals. The patterns of light, or the images and graphics formed by the display device may be formed by individual light emitting structures, such as organic light emitting diodes (OLEDs). OLEDs may be optoelectronic devices having several layers of organic materials, and may include a pair of electrodes, and multiple layers of electroluminescent materials between the electrodes. For example, an OLED may typically include a substrate, an anode, a hole-transporting layer made of an organic compound, an organic luminescent layer with suitable dopants, an organic electron transporting layer, and a cathode.
Light emitting structures, including OLEDs, may be prone to degradation under certain environmental conditions such as oxygen, moisture, chemicals, or other contaminants. For example, water vapor and oxygen ingress over time may cause degradation of light emitting polymers, undesired reactions at the electrode-organic layer interfaces, corrosion of metals, or undesired migration of ionic species, etc. Such degradation may result in the growth of dark spots, delamination, and/or the shrinking of the emissive areas of the light emitting structure. Thus, dark spots, delamination, and/or shrinking of the emissive areas of such structures may affect the quality and/or uniformity of the image displayed.
To minimize the degradation of light emitting structures, the structures may be hermetically sealed with barrier materials to protect against adverse environmental conditions. For example, glass and metal caps with epoxy sealants and desiccants are typically used to seal the structures. However, such encapsulation methods may not be the most cost effective methods for sealing the structures. Other methods of reducing degradation may include thin film encapsulation, such as a graded ultra high barrier (UHB) technology. However, the process time (i.e., the time required to fully encapsulate a light emitting structure) for thin film encapsulation, may be longer than the process time when using a typical glass and epoxy encapsulation process.